Sampling the contents of a well is commonly done for purposes ranging from bacterial analysis of potable water wells to chemical analysis of oil and gas supply wells. With increased environmental protection regulations, more sampling wells, particularly water wells, have been drilled.
Prior to sampling a well, the standing fluid must be removed or purged so that what is sampled is fresh fluid influx to the well rather than stagnant fluid. Because fluid extracted from a well may become contaminated, it is preferred to avoid re-injecting the fluid into the well. Moreover, if the fluid is already contaminated (hence the reason for taking the samples) it is preferred to contain the contamination and not spread it by dumping it on the ground. In the United States, extracted well fluid is prohibited by regulation from being re-injected into the well or dumped onto the ground. Hence, handling the volume of purged fluid adds significant expense to the sampling procedure and as more sampling is done, the cost rises proportionately.
Present methods of purging involve removing two to four well volumes into a container. If sampling must be done more than once, with extended period of time between sampling, the well must be purged prior to each sampling. Thus, there is a need in the well sampling industry for a means and method of purging and sampling that would reduce the amount of water taken from wells for purposes of sampling.